 |
This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (July 2010) |
Cinepak is a video codec developed by Peter Barrett at SuperMac Technologies, and released in 1991 with the Video Spigot, and then in 1992 as part of Apple Computer's QuickTime video suite. It was designed to encode 320x240 resolution video at 1x (150 kbyte/s) CD-ROM transfer rates. The codec was ported to the Microsoft Windows platform in 1993. It was also used on first-generation and some second-generation CD-ROM game consoles, such as the Atari Jaguar CD, Sega CD, Sega Saturn, and 3DO.
It was the primary video codec of early versions of QuickTime and Microsoft Video for Windows, but was later superseded by Sorenson Video, Intel Indeo, and most recently MPEG-4 and H.264. However, movies compressed with Cinepak are generally still playable in most media players.
Cinepak is based on vector quantization, which is a significantly different algorithm from the discrete cosine transform (DCT) algorithm used by most current codecs (in particular the MPEG family, as well as JPEG). This permitted implementation on relatively slow CPUs (video encoded in Cinepak will usually play fine even on a 25 MHz Motorola 68030, consoles like the Sega CD usually used even slower CPUs, e.g. a 2.5MHz 68000), but tended to result in blocky artifacting at low bitrates, which explained the criticism levelled at the FMV-based video games.
Cinepak divides a movie into key images and intra-coded images. Each image is divided into a number of horizontal bands which have individual 256-color palettes transferred in the key images. Each band is subdivided into 4x4 pixel blocks. The compressor uses vector quantization to determine the one or two band palette colors which best match each block and encodes runs of blocks as either one color byte or two color bytes plus a 16-bit vector which determines which pixel gets which color, similarly to S3 Texture Compression. The data rate can be controlled within a narrow range by adjusting the rate of key versus intra-coded frames and by adjusting the permitted error in each block and the block run-length.
The original name of this codec was CompactVideo, which is why its FourCC identifier is "CVID".
Cinepak files tend to be about 70% larger than similar quality MPEG-4 or Ogg files.
External links [link]
|
||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||
 |
This multimedia software-related article is a stub. You can help Wikipedia by expanding it. |
